// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "content/browser/notification_service_impl.h"

#include "base/lazy_instance.h"
#include "base/threading/thread_local.h"
#include "content/public/browser/notification_observer.h"
#include "content/public/browser/notification_types.h"

namespace content {

namespace {

    base::LazyInstance<base::ThreadLocalPointer<NotificationServiceImpl>>
        lazy_tls_ptr = LAZY_INSTANCE_INITIALIZER;

} // namespace

// static
NotificationServiceImpl* NotificationServiceImpl::current()
{
    return lazy_tls_ptr.Pointer()->Get();
}

// static
NotificationService* NotificationService::current()
{
    return NotificationServiceImpl::current();
}

// static
NotificationService* NotificationService::Create()
{
    return new NotificationServiceImpl;
}

// static
bool NotificationServiceImpl::HasKey(const NotificationSourceMap& map,
    const NotificationSource& source)
{
    return map.find(source.map_key()) != map.end();
}

NotificationServiceImpl::NotificationServiceImpl()
{
    DCHECK(current() == NULL);
    lazy_tls_ptr.Pointer()->Set(this);
}

void NotificationServiceImpl::AddObserver(NotificationObserver* observer,
    int type,
    const NotificationSource& source)
{
    // We have gotten some crashes where the observer pointer is NULL. The problem
    // is that this happens when we actually execute a notification, so have no
    // way of knowing who the bad observer was. We want to know when this happens
    // in release mode so we know what code to blame the crash on (since this is
    // guaranteed to crash later).
    CHECK(observer);

    NotificationObserverList* observer_list;
    if (HasKey(observers_[type], source)) {
        observer_list = observers_[type][source.map_key()];
    } else {
        observer_list = new NotificationObserverList;
        observers_[type][source.map_key()] = observer_list;
    }

    observer_list->AddObserver(observer);
#ifndef NDEBUG
    ++observer_counts_[type];
#endif
}

void NotificationServiceImpl::RemoveObserver(NotificationObserver* observer,
    int type,
    const NotificationSource& source)
{
    // This is a very serious bug.  An object is most likely being deleted on
    // the wrong thread, and as a result another thread's NotificationServiceImpl
    // has its deleted pointer in its map.  A garbge object will be called in the
    // future.
    // NOTE: when this check shows crashes, use BrowserThread::DeleteOnIOThread or
    // other variants as the trait on the object.
    CHECK(HasKey(observers_[type], source));

    NotificationObserverList* observer_list = observers_[type][source.map_key()];
    if (observer_list) {
        observer_list->RemoveObserver(observer);
        if (!observer_list->might_have_observers()) {
            observers_[type].erase(source.map_key());
            delete observer_list;
        }
#ifndef NDEBUG
        --observer_counts_[type];
#endif
    }
}

void NotificationServiceImpl::Notify(int type,
    const NotificationSource& source,
    const NotificationDetails& details)
{
    DCHECK_GT(type, NOTIFICATION_ALL) << "Allowed for observing, but not posting.";

    // There's no particular reason for the order in which the different
    // classes of observers get notified here.

    // Notify observers of all types and all sources
    if (HasKey(observers_[NOTIFICATION_ALL], AllSources()) && source != AllSources()) {
        for (auto& observer : *observers_[NOTIFICATION_ALL][AllSources().map_key()])
            observer.Observe(type, source, details);
    }

    // Notify observers of all types and the given source
    if (HasKey(observers_[NOTIFICATION_ALL], source)) {
        for (auto& observer : *observers_[NOTIFICATION_ALL][source.map_key()])
            observer.Observe(type, source, details);
    }

    // Notify observers of the given type and all sources
    if (HasKey(observers_[type], AllSources()) && source != AllSources()) {
        for (auto& observer : *observers_[type][AllSources().map_key()])
            observer.Observe(type, source, details);
    }

    // Notify observers of the given type and the given source
    if (HasKey(observers_[type], source)) {
        for (auto& observer : *observers_[type][source.map_key()])
            observer.Observe(type, source, details);
    }
}

NotificationServiceImpl::~NotificationServiceImpl()
{
    lazy_tls_ptr.Pointer()->Set(NULL);

#ifndef NDEBUG
    for (int i = 0; i < static_cast<int>(observer_counts_.size()); i++) {
        if (observer_counts_[i] > 0) {
            // This may not be completely fixable -- see
            // http://code.google.com/p/chromium/issues/detail?id=11010 .
            VLOG(1) << observer_counts_[i] << " notification observer(s) leaked "
                                              "of notification type "
                    << i;
        }
    }
#endif

    for (int i = 0; i < static_cast<int>(observers_.size()); i++) {
        NotificationSourceMap omap = observers_[i];
        for (NotificationSourceMap::iterator it = omap.begin();
             it != omap.end(); ++it)
            delete it->second;
    }
}

} // namespace content
